This work investigates the historical and clinical evolution of multiple personality and possession states, seeking to reconcile disparate interpretations of fragmented consciousness. Adam Crabtree, a psychotherapist and historian of psychology, utilizes extensive archival research and clinical case studies to trace how these phenomena have been categorized from the eighteenth century to the modern era. He argues that the shift from spiritualistic explanations to psychological frameworks reflects broader changes in how Western society understands the boundaries of the self.

Experts recognize this text as a significant historical survey that bridges the gap between early psychical research and modern clinical psychology. Readers frequently note the academic density of the prose, which provides a thorough, scholarly foundation for those interested in the history of dissociative phenomena.